The art of barbecue cooking has proliferated with the advent of the modern propane gas fired barbecue grill. Such gas grills are extremely convenient in that the cooking fire is instantaneous and the barbecue grill achieves the desired cooking temperature within a few minutes. In contrast, the old-fashioned charcoal grill is inconvenient in that it takes considerably longer getting to the point where the coals are ready for cooking, usually requires a starter fuel, and totally consumes the charcoal during cooking, thus requiring replacement with new charcoal for each cooking session. A charcoal fire, however, releases smoke which serves to add flavor to the food, a property not shared by the gas fired grill. Therefore, various devices and methods have been used to generate flavoring smoke in a gas fired barbecue grill, in order to enhance the flavor of food prepared on a gas grill.
A combustible fuel element for use in barbecue grills was patented by Orsing in 1978 (U.S. Pat. No. 4,095,957). The Orsing invention is a fuel element, such as charcoal, coal, wood chips and coke, impregnated with a combustible fluid to aid in igniting the fuel. The Orsing fuel elements are encased in a porous, noncombustible casing made preferably of nonwoven glass fiber. The fuel elements so encased are further enclosed in an envelope of nonporous, gas and fluid impermeable inert flexible plastic sheet material acting as the outer container for holding the product on the shelf. This outer container, or envelope, must be removed and discarded before placing the Orsing fuel elements in the barbecue for igniting. Orsing's fuel elements do not solve the problem of creating smoke in a gas fired grill because they are not suitable for use in a gas grill but, rather, are intended for producing the cooking fire in a conventional barbecue grill, and in so doing also produce smoke for flavoring the food.
A smoke generating device suitable for use in a gas barbecue was invented by Gaines and was issued U.S. Pat. No. 4,779,525 in 1988. The Gaines device includes a noncombustible container, preferably formed in the shape of a cylinder, having at least one smoke exhaust hole, but preferably having a plurality of holes only in the top of the container so as to limit the rate of air flow through the container and thereby promote slow smoldering of the smoke producing material, including wood chips. The Gaines invention teaches that the size of the holes in the container is of crucial importance. Gaines points out that if the holes are too large then too much air will enter the container and the smoke producing material will ignite and combust, which is undesirable for proper smoke production. Gaines, in addition, teaches that large holes admit flaming fat dripping from the meat cooking above the smoke generating device, also helping to ignite the contents of the cylinder and preventing proper smoke generation. Accordingly, the Gaines device has multiple small holes on its top side and must be placed into the barbecue in its proper orientation for the smoke to be released through such holes. An alternate embodiment of the Gaines invention is an aluminum cup filled with the smoke generating material and covered with a perforated piece of foil which is crimped to the lip of the cup; a combustible cover is provided over the perforations in the foil. The Gaines invention specifically teaches that for proper performance the smoke generating device must have multiple small holes rather than one large hole, to thereby limit oxygen supply to the smoke generating material and to prevent burning fat drippings from igniting the smoke generating material. The Gaines container, therefore, has the disadvantage of requiring more complex manufacturing to produce and to package for sale, since the multiple holes must be first formed and later covered for handling during shipping and sale.
Barbecue flavoring blocks invented by Holmes were granted U.S. Pat. No. 4,941,889 in 1990. The Holmes invention consists of wood chips bound together by a hard gelatin in water solution, which may include added flavorings to enhance the natural smoke flavor of the wood. The blocks are pasteurized to eliminate harmful microorganisms, are then coated with a protective coating, and packaged for sale. In use, the Holmes blocks are placed directly into the barbecue grill fire and produce smoke as the hard gelatin coating melts. If so used in a gas fired barbecue grill, the hard gelatin, added flavorings, wood resins and ash would drop onto the burners and foul the gas jets, affecting the operation of the barbecue. Holmes teaches that indirect heating of the blocks is preferred when the heat source for cooking is gas or electric. Indirect heating is achieved by placing the blocks in a separate drawer or location of the barbecue. Additionally, Holmes indicates that it is preferred that the blocks receive an insufficient source of oxygen during combustion, so that they do not burn but smoke instead. The Holmes invention, however, offers no solutions to the problems of how to indirectly heat the blocks so that the barbecue's burners are not fouled, or how to provide insufficient oxygen to the blocks during cooking.
A disposable/refillable smoke cartridge for gas barbecue grills was disclosed by Cofer in 1991 in U.S. Pat. No. 5,048,406. The Cofer device is preferably a cylindrical cartridge containing wood chips. The cartridge may be partially opened on one side by a pull-tab ring to allow smoke to escape, or may have small perforations on one end of its top or side walls for the same purpose. The cartridge may also have small perforations on one end of its bottom wall to provide for draft ventilation. Cofer continues the approach previously taught by Gaines, using only small openings into the cylinder or placing an opening in a recess, under an extension tube, or behind a shield to prevent grease from dripping into the cylinder, causing a fire in the wood chips. In addition, Cofer recommends that the cylinder be tilted with the smoke releasing end of the cylinder further elevated over the fire than the opposite end of the cylinder. Cofer states that this elevation is useful for optimum emission of smoke, and for lessening the chance that the wood chips will catch fire since the elevation keeps part of the wood chips and gases farther from direct heat than the other end of the cylinder. Cofer touts as a further advantage of the invention the fact that the wood chips need not be presoaked. In addition, Cofer states that if the device catches fire it can be readily blown out or doused by splashing with water, although it is difficult to see how water could be splashed onto the fire inside a device having such small access holes.